The 41-year-old, who played a goblin in 2001's "Harry Potter and the Sorcerer's Stone," flashed at a student on a train to Manchester in north England and took a picture of her horrified friend on a cellphone. The act put him in breach of a 20-week suspended jail sentence which was handed to him after he performed a sex act in front of a teenager on a train journey in 2010 and he now faces imprisonment.

During a hearing at Manchester Crown Court, Judge Roger Thomas told the actor, "The bottom line is you are in breach of a suspended sentence. The normal consequence of that is to prison you go and that may well have to be the outcome.

"But this is an unusual sort of case and the judge will be informed by the Probation Service about what's been going on over the last 12 months, and what sort of risk you pose hereafter."